Ground — Based scatterometer measurements of periodic surface roughness and correlation length for remote sensing

Abstract

This paper describes the effect of periodic surface roughness ( H rms ) and correlation length (Λ) on the scattering coefficient ( σ 0). The scattering co-efficient of a surface is governed by both the dielectric properties and the roughness parameter of that surface. So, in this paper, it is attempted to highlight the effect of these surface parameter on the σ 0 at X-band (9.5 GHz) frequency. The angular and polarization dependence of roughness and correlation length has also been observed at X- band. For this purpose, out door observations have been carried out using an X- band scatterometer for various periodic surface roughness and correlation lengths. In this study, we have taken soil moisture as a constant. Experimentally observed data were utilized to provide a composite σ 0 equation model accounting for individual effects in regression analysis. Experimentally observed co-polarized ratios (( p = σ HH 0 σ VV 0 )) are compared with a semi-empirically model (Oh et al., 1992) for the co-polarized ratio. Good agreement has been observed between experimentally observed p and empirically obtained p. Multiple and partial regression analyses have also been carried out for predicting the dependence of σ 0 on H rms and Λ more accurately. It was found that dependence of σ 0 on H rms is much more significant in comparison to correlation length at higher incidence angle (θ > 30 degree) while lower incidence angle (θ < 30 degree) is more significant to observe the effect of Λ for both like polarization. The 40-degree incidence angle is found the best suitable angle to observe the H rms and Λ effect on σ 0 . W-polarization is more sensitive than VV-polarization for observing the periodic surface roughness at X- band. 0 2003 cospar.